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Field effect transistors are often used as high-speed electronic switches – meet one of them under the name IRF540!
IRF540 - general characteristics
The IRF540 is an N-type channel MOSFET housed in a TO-220AB package for through-hole mounting. The specially designed internal semiconductor structure of this transistor has made it possible to achieve an extremely low turn-on resistance between the drain and the source, combined with a high switching speed and a strengthened design for electro-thermal resistance, known from unipolar HEXFET-type transistors. The result is a high-performance and reliable semiconductor element with a wide range of applications in professional and consumer electronics. The TO-220 package that houses the IRF540 transistor is a very popular choice for many applications, and its design allows a maximum power dissipation of 50 W. The low thermal resistance and low manufacturing cost of the TO-220 chassis place it as one of the best choices for these semiconductors.
The most important parameters of the IRF540 transistor
- Housing type: TO-220AB
- Conduction type: unipolar transistor, N-type channel
- Maximum drain-source voltage: 100V
- Maximum drain-gate voltage: 100V
- Maximum gate-to-source voltage: +/- 20V
- Maximum continuous drain current: 33A
- Maximum power dissipated: 120W
- Typical drain-source resistance in the ON state: 32mΩ
- Maximum drain-source resistance at full transistor load: 65mΩ
- Permissible operating temperature range: from -55*C to +175*C
IRF540 transistor - applications
Typical applications for the IRF540 transistor are N-type channel MOSFET power transistors, which are excellent for use in DC boost converter circuits, switching power supplies, pulse transformer circuits, power amplifiers, PWM motor controllers, as well as in converters operating in buck and boost topologies.
IRF540 transistor in practice
A MOSFET transistor is a voltage-controlled semiconductor device that can be turned on or off by providing a sufficiently high threshold voltage relative to the gate (Vgs) relative to the source. The IRF540 transistor is an N-channel MOSFET, which means that no current will flow between the drain and source leads when no voltage is applied to the transistor’s gate. On the other hand, when a voltage exceeding a threshold value is applied to the transistor’s gate, the drain-source circuit will be closed and electric current will flow through it.
Since it is an N-channel transistor, the load circuit controlled by it should always be connected above the lead. When we turn on a MOSFET transistor by supplying the appropriate voltage to its gate, it will be on all the time and will conduct until a zero voltage appears back at the gate. To avoid this problem, we should always connect a pull-down resistor to ground between the gate and the source. In applications such as controlling the speed of electric motors or controlling the dimming of lights, we should use a PWM signal to control the MOSFET transistor. Here we should bear in mind that then the gate capacitance of the MOSFET transistor can create conditions for reverse current flow. For this reason, we should use an additional resistor R2, which effectively nullifies the effect of the capacitive effect of the transistor’s gate.
Connection of the IRF540 transistor
First, connect the source pin to ground or the negative rail of the supply voltage. The drain should be connected to the positive rail of the supply voltage, through the load whose switching on and off you want to control. The gate, or control electrode, is connected to the trigger source. The preferred trigger source for the gate should give a voltage of 5 V, according to the TTL technology standard. If the trigger source is not a logic circuit or microcontroller, make sure that the gate of the transistor is connected to ground through a resistor. If our transistor is to be used to switch inductive loads, such as transformers or motors, we should connect an overvoltage protection diode in parallel to the load. We connect its cathode to the positive rail of the supply voltage, and its anode to the drain of the transistor. In this way, we will protect the transistor from damage due to overvoltages resulting from switching off circuits with inductances.
Index N in the designation
When selecting a MOSFET trans istor for our application, it is worth paying attention to additional indices in the naming in addition to its basic name, and this also applies to the IRF540 transistor discussed in the following article. After all, there is the IRF540N transistor, which is made using a technology that takes advantage of the reduced area of the silicon wafer, thus enabling lower production costs. In contrast, the IRF540N transistor, note the subscript “N” in its name, is made using planar technology, which uses a larger area of the silicon wafer, thus achieving higher current throughput. What also distinguishes the IRF540N from its counterpart without the “N” in the designation is the lower maximum resistance of the drain-source junction in the ON state, which is 44 mΩ, while for the IRF540 it is only 77 mΩ. The difference in the maximum conduction current is also important, for the IRF540 it is 23 A, while for the IRF540N it is 33 A, but these values can vary depending on the specifications of the specific component manufacturer.
IRF540 - replacements
Replacements for the IRF540 transistor are commercially available, which are similar with respect to each other in the most important parameters, although they may have a different pinout and type of housing, which should be taken into account in the design of electronic devices as well as in the assembly process. Replacements for the IRF540 transistor include:
- 2N3055,
- RFP30N06,
- IRFZ44,
- IRF3205,
- IRF1310N,
- IRF3415,
- IRF3710,
- IRF3710Z,
- IRF3710ZG,
- IRF8010,
- IRFB260N,
- IRFB4110,
- IRFB4115,
- IRFB4115G,
- IRFB4127,
- IRFB4227,
- IRFB4233,
- IRFB4310,
- IRFB4310G,
- IRFB4310Z,
- IRFB4310ZG,
- IRFB4321,
- IRFB4321G,
- IRFB4332,
- IRFB4410,
- IRFB4410Z,
- IRFB4410ZG,
- IRFB4110G,
- IRFB4510,
- IRFB4510G,
- IRFB4610,
- IRFB4615,
- IRFB4710,
- IRFB52N15D,
- IRFB5615,
- IRFB59N10D,
- IRFB61N15D.
